Fluorinated electrolyte compositions
Electrolyte compositions containing a solvent mixture comprising 2,2,-difluoroethyl acetate and ethylene carbonate are described. The electrolyte compositions are useful in electrochemical cells, such as lithium ion batteries.
1. An electrolyte composition comprising:
(a) at least one electrolyte salt;
(b) a solvent mixture comprising ethylene carbonate at a concentration of about 10% to about 50% by weight of the solvent mixture; and CH 3 CO 2 CH 2 CF 2 H at a concentration of about 50% to about 90% by weight of the solvent mixture; and
(c) fluoroethylene carbonate at a concentration of about 0.01% to less than 2% by weight of the electrolyte composition.
2. The electrolyte composition of claim 1 , wherein the electrolyte salt is selected from one or more members of the group consisting of:
lithium hexafluorophosphate,
LiPF 3 (CF 2 CF 3 ) 3 ,
lithium bis(trifluoromethanesulfonyl)imide,
lithium bis (perfluoroethanesulfonyl)imide,
lithium (fluorosulfonyl) (nonafluorobutanesulfonyl)imide,
lithium bis(fluorosulfonyl)imide,
lithium tetrafluoroborate,
lithium perchlorate,
lithium hexafluoroarsenate,
lithium trifluoromethanesulfonate,
lithium tris (trifluoromethanesulfonyl)methide,
lithium bis(oxalato)borate,
lithium difluoro(oxalato)borate,
Li 2 B 12 F 12-x H x where x is equal to 0 to 8, and
a mixture of lithium fluoride and an anion receptor.
3. The electrolyte composition of claim 2 wherein the electrolyte salt is lithium hexafluorophosphate.
4. The electrolyte composition of claim 1 , wherein the ethylene carbonate comprises about 30% by weight of the solvent mixture and the CH 3 CO 2 CH 2 CF 2 H comprises about 70% by weight of the solvent mixture.
5. The electrolyte composition of claim 1 , wherein the fluoroethylene carbonate comprises about 1% by weight of the electrolyte composition.
6. An electrochemical cell comprising:
(a) a housing;
(b) an anode and a cathode disposed in said housing and in conductive contact with one another;
(c) an electrolyte composition disposed in said housing and providing an ionically conductive pathway between said anode and said cathode, wherein the electrolyte composition comprises:
(i) at least one electrolyte salt;
(ii) a solvent mixture comprising ethylene carbonate at a concentration of about 10% to about 50% by weight of the solvent mixture; and CH 3 CO 2 CH 2 CF 2 H at a concentration of about 50% to about 90% by weight of the solvent mixture; and
(iii) fluoroethylene carbonate at a concentration of about 0.01% to less than 2% by weight of the electrolyte composition; and
(d) a porous separator between said anode and said cathode.
7. The electrochemical cell of claim 6 , wherein the ethylene carbonate comprises about 30% by weight of the solvent mixture and the CH 3 CO 2 CH 2 CF 2 H comprises about 70% by weight of the solvent mixture.
8. The electrochemical cell of claim 6 , wherein the fluoroethylene carbonate comprises about 1% by weight of the electrolyte composition.
9. The electrochemical cell of claim 6 , wherein said electrochemical cell is a lithium ion battery.
10. An electronic device comprising an electrochemical cell according to claim 6 .